Method of coagulating a fluoro-elastomer from an aqueous dispersion thereof

Abstract

A process for coagulating a fluoro-elastomer in an aqueous medium which comprises adding to an aqueous acidic medium thereof an organic base or salt thereof which acts as a vulcanization accelerator.

What is claimed is: 
     
       1. A process for coagulating a fluoro-elastomer in an aqueous medium which comprises adding to an aqueous acidic medium thereof an organic base or salt thereof which acts as a vulcanization accelerator wherein said organic base of salt is secondary or tertiary aliphatic, cycloaliphatic, heterocyclic or araliphatic monofunctional amine having a boiling point of greater than 150° C, a quaternary aliphatic, cycloaliphatic, araliphatic or heterocyclic ammonium compound, a quanternary aliphatic, cycloaliphatic, araliphatic phosphonium compound or a mixture thereof. 
     
     
       2. A process according to claim 1 wherein the amount of organic base or salt thereof is between 0.2 and 20 millimoles per 100 g of anhydrous elastomer. 
     
     
       3. A process according to claim 1 wherein the organic base or salt thereof is a quaternary ammonium compound of the formula ##STR5## wherein R 1 , R 2  and R 3  and R 4  each independently represent a C 1  -C 20  alkyl group, a fluroalkyl group having 1 to 20 carbon atoms, an aralkyl group wherein the alkyl portion contains 1 to 20 carbon atoms, a polyhydroxy alkylene or polyhydroxy fluoroalkylene radical wherein at least two of such radicals are alkyl or aralkyl radicals and X is hydroxyl, halide, sulfate, perchlorate, carbonate, pentachlorothiophenylate, tetrafluoroborate, hexafluorosilicate, hexafluorophosphate, dimethylphosphate or C 1  -C 20  alkyl, aralkyl or aryl carboxylate or aryl dicarboxylate. 
     
     
       4. A process according to claim 1 wherein the organic base or salt thereof is a quaternary ammonium compound having the general formula ##STR6## wherein R 5  is a C 1  -C 20  alkyl radical and X is hydroxyl, halide, sulfate, perchlorate, carbonate, pentachlorothiophenylate, tetrafluoroborate, hexafluorosilicate, hexafluorophosphate, dimethylphosphate or a C 1  -C 20  alkyl, aralkyl or aryl carboxylate or aryl dicarboxylate. 
     
     
       5. A process according to claim 1 wherein the quaternary ammonium compound has the formula ##STR7## wherein R 5  represents a C 1  -C 20  alkyl radical and X represents hydroxyl, halide, sulfate, perchlorate, carbonate, pentachlorothiophenylate, tetrafluoroborate, hexafluorosilicate, hexafluorophosphate, dimethylphosphate or a C 1  -C 20  alkyl, aralkyl or aryl carboxylate or aryl dicarboxylate. 
     
     
       6. A process according to claim 1 wherein the organic base is a quaternary ammonium halide selected from the group consisting of tetrabutylammonium iodide, hexadecyltrimethylammonium chloride and methyltrioctylammonium chloride. 
     
     
       7. A process according to claim 1 wherein the organic base is a quaternary phosphonium compound selected from the group consisting of butyltriphenylphosphonium bromide, butyltriphenylphosphonium chloride, dodecyltriphenylphosphoniumbromide, dodecyltriphenylphosphonium chloride, benzyltriphenylphosphonium chloride, benzyltriphenylphosphonium bromide, allyltriphenylphosphonium chloride and allyltriphenylphosphonium bromide, or a corresponding quaternary phosphonium base thereof. 
     
     
       8. A process according to claim 1 wherein a quaternary phosphonium compound is employed as the organic base or salt which quaternary ammonium compound contains four organic radicals bounded to the phosphorus atom each of which may be identical or different each of which radical contains 1 to 20 carbon atoms and is linear, branched or cyclic, saturated or unsaturated and can contain a nitrogen, oxygen or sulfur hetero atom in the chain and the anion is selected from the group consisting of hydroxyl, chloride, bromide, methoxy, acetate, mercaptate, sulfate, bisulfate and perchlorate. 
     
     
       9. A process according to claim 8 wherein the organic radical bonded to the phosphorus atom of the quaternary phosphonium compound is an alkyl or alkenyl group. 
     
     
       10. A process according to claim 1 wherein a quaternary ammonium compound is employed as the organic base or salt which quaternary ammonium compound is in the form of a salt which has a solubility in water of less than 0.2 g per 100 ml. determined at 25° C. 
     
     
       11. A process according to claim 10 wherein said ammonium salt is selected from the group consisting of trimethylhexadecylammonium chloride and methyltrioctylammonium chloride. 
     
     
       12. A process according to claim 1 wherein the organic base is a quaternary phosphonium perchlorate, the four organic radicals bonded thereto each having between 1 and 20 carbon atoms in the chain which radicals are linear, branched, or cyclic, saturated or unsaturated and can contain an oxygen, nitrogen or sulfur atom in the chain. 
     
     
       13. A process according to claim 12 wherein each organic radical bonded to the phosphorus atom is alkyl, alkenyl, aryl or aralkyl. 
     
     
       14. A process according to claim 1 wherein the organic base or salt thereof is a quaternary aliphatic ammonium perchlorate wherein the aliphatic groups each contain 1 to 20 carbon atoms in the chain. 
     
     
       15. A process according to claim 14 wherein the quaternary aliphatic ammonium perchlorate is selected from the group consisting of tetrabutylammonium perchlorate, hexadecyltrimethylammonium perchlorate, methyltrioctylammonium perchlorate, n-dodecyltriethylammonium perchlorate and n-octyltri-n-butylammonium perchlorate. 
     
     
       16. A process according to claim 1 wherein the amount of organic base added to the dispersion is between 0.5 and 5 millimoles per 100 grams of anhydrous elastomer. 
     
     
       17. A process according to claim 1 wherein the organic base is selected from the group consisting of tetramethylammonium hydroxide, tetramethylammoniumpentachlorothiophenolate, lauryldimethylnaphthylmethylammonium chloride, laurylisoquinoline chloride, distearyldimethylammonium chloride, tetrahexylammonium tetrafluoroborate, methyltrioctylammonium oxalate, hexadecylpyridinium chloride, benzyltrioctylammonium chloride, diisobutylphenoxyethoxyethyldimethoxybenzyl chloride, methoxyethoxyethyltrioctylammonium chloride, and 2,2,3,3-tetrafluoropropyltrioctylammonium chloride. 
     
     
       18. A process according to claim 1 wherein the organic base is selected from the group consisting of dibutylamine, dicyclohexylamine, tributylamine and ethyldicyclohexylamine or a salt thereof. 
     
     
       19. A process according to claim 1 wherein there is additionally added to the fluoro-elastomer dispersion a hydroxy compound which acts as a vulcanizer. 
     
     
       20. A process according to claim 19 wherein the hydroxy compound is a mononuclear or polynuclear aromatic hydroxy compound. 
     
     
       21. A process according to claim 20 wherein said mononuclear, polynuclear aromatic hydroxy compound has a solubility in water of less than 1 g per 100 ml. water determined at 25° C. 
     
     
       22. A process according to claim 20 wherein the hydroxy compound has the formula ##STR8## wherein A is a bifunctional aliphatic, cycloaliphatic or aromatic radical having 1 to 13 carbon atoms, a thio, oxy, carbonyl, sulfonyl or sulfone radical or a radical of the formula ##STR9## X is 0 or 1 and n is 1 or 2. 
     
     
       23. A process according to claim 19 wherein the hydroxy compound is a di-, tri- or tetra hydroxybenzene, naphthylene or anthracene. 
     
     
       24. A process according to claim 19 wherein the hydroxy compound is selected from the group consisting of a dihydroxybiphenyl, a dihydroxy compound of a bisphenol, 2,2', 4,4'-tetrahydroxybenzophenone, pyrocatechol, resorcinol, 2-methylresorcinol, 5-methylresorcinol, 2-methylhydroquinone, 2,5-dimethylhydroquinone, 2-tert.-butyl-hydroquinone, hydroquinone, 1,4,9,10-tetrahydroxyanthracene, 2,4-dihydroxybenzoic acid, 2,6-dihydroxyanthraquinone, 3,6-dihydroxyanthraquinone, pyromellitic acid-bis-(p-hydroxyphenylimide), 2,4-dihydroxyacetophenone, 4,4'-dihydroxydiphenylsulfoxide, 2,4-dibenzoresorcinol, 2,4,5-trihydroxybutryophenone, dihydroxybenzophenone, phenolphthalein and 2,4-dihydroxybenzaldehyde. 
     
     
       25. A process according to claim 24 wherein the hydroxy compound is a dihydroxy compound of a bisphenol which bisphenol is selected from the group consisting of bisphenol A, bisphenol AF, bisphenol S and bisphenol Z. 
     
     
       26. A process according to claim 19 wherein the hydroxy compound is added in the form of a solution in methanol, ethanol, acetone, dimethylformamide or dimethylsulfoxide. 
     
     
       27. A process according to claim 2 wherein the organic base is benzyltriphenylphosphonium perchlorate. 
     
     
       28. A process according to claim 2 wherein the organic base is allyltriphenylphosphonium perchlorate. 
     
     
       29. A process according to claim 2 wherein the organic base is n-butyl-triphenylphosphonium perchlorate. 
     
     
       30. A process according to claim 2 wherein the organic base is n-dodecyltriethylammonium perchlorate. 
     
     
       31. A process according to claim 2 wherein the organic base is benzyltriethylammonium perchlorate. 
     
     
       32. A process according to claim 2 wherein the organic base is n-octyl-tri-n-butylammonium perchlorate. 
     
     
       33. A process according to claim 2 wherein the organic base is benzyltriphenylphosphonium chloride. 
     
     
       34. A process according to claim 2 wherein the organic base is methyltrioctylammonium chloride. 
     
     
       35. A process according to claim 2 wherein the organic base is ethyldicyclohexylamine. 
     
     
       36. A process according to claim 2 wherein the organic base is tetra-n-butylammonium perchlorate. 
     
     
       37. A process according to claim 2 wherein the organic base is allyltriphenylphosphonium chloride. 
     
     
       38. A process according to claim 2 wherein the organic base is dicyclohexylamine. 
     
     
       39. A process according to claim 2 wherein the organic base is tetrabutylammonium iodide. 
     
     
       40. A process according to claim 19 wherein the hydroxy compound is added in an amount of between 5 and 15 millimoles per 100 g of water-free fluoro-elastomer. 
     
     
       41. A process according to claim 40 wherein the hydroxy compound is bisphenol A. 
     
     
       42. A process according to claim 40 wherein the hydroxy compound is phenolphthalein. 
     
     
       43. A process according to claim 40 wherein the hydroxy compound is bisphenol Z. 
     
     
       44. A process according to claim 40 wherein the hydroxy compound is p,p'-biphenol. 
     
     
       45. A process according to claim 40 wherein the hydroxy compound is bisphenol AF. 
     
     
       46. A process according to claim 40 wherein the hydroxy compound is bisphenol S. 
     
     
       47. A process according to claim 40 wherein the hydroxy compound is 2,4,-dihydroxybenzophenone.